Cupola furnaces for the manufacture of steel have been used for many years. In such systems, ore, limestone and coke are introduced into a cupola furnace and the coke is burned. When the operation is concluded, molten slag floating on the surface of the melted iron is drawn off and subsequently the iron is removed. The temperature of the slag at this point is in the neighborhood of 2000.degree. F. and it has been the practice to pour the slag into large containers or buckets in which the slag may cool. The slag then, being a waste product, must be disposed of in some manner, and in one system the slag is broken up into small particles and used for road surfacing and the like.